Arylsulfur pentafluoride compounds are used to introduce one or more sulfur pentafluoride groups into various commercial organic molecules. In particular, arylsulfur pentafluorides are useful (as product or intermediate) in the development of liquid crystals (Eur. J. Org. Chem. 2005, pp. 3095-3100) and as bioactive chemicals such as fungicides, herbicides, insecticides, paraciticides, anti-cancer drugs, enzyme inhibitors, antimalarial agent, and other like materials [see, for example, J. Pestic. Sci., Vol. 32, pp. 255-259 (2007); Chimia Vol. 58, pp. 138-142 (2004); Chem Bio Chem 2009, 10, pp. 79-83; Tetrahedron Lett. Vol. 51 (2010), pp. 5137-5140; J. Med. Chem. 2011, Vol. 54, pp. 3935-3949; J. Med. Chem. 2011, Vol. 54, pp. 5540-5561; WO 99/47139; WO 2003/093228; WO 2006/108700 A1; US 2005/0197370; U.S. Pat. No. 7,381,841 B2; US 2008/176865; U.S. Pat. No. 7,446,225 B2; WO 2010/138588 A2; WO 2011/44184].
Arylsulfur pentafluorides have been synthesized using one of the following synthetic methods: (1) fluorination of diaryl disulfies or arylsulfur trifluoride with AgF2 [see J. Am. Chem. Soc., Vol. 82 (1962), pp. 3064-3072, and J. Fluorine Chem. Vol. 112 (2001), pp. 287-295]; (2) fluorination of bis(nitrophenyl) disulfides, nitrobenzenethiols, or nitrophenylsulfur trifluorides with molecular fluorine (F2) [see Tetrahedron, Vol. 56 (2000), pp. 3399-3408; Eur. J. Org. Chem., Vol. 2005, pp. 3095-3100; and U.S. Pat. No. 5,741,935]; (3) fluorination of diaryl disulfides or arenethiols with F2, CF3OF, or CF2(OF)2 in the presence or absence of a fluoride source (see US Patent Publication No. 2004/0249209 A1); (4) fluorination of diaryl disulfides with XeF2 [see J. Fluorine Chem., Vol. 101 (2000), pp. 279-283]; (5) reaction of 1,4-bis(acetoxy)-2-cyclohexene with SF5Br followed by dehydrobromination or hydrolysis and then aromatization reactions [see J. Fluorine Chem., Vol. 125 (2004), pp. 549-552]; (6) reaction of 4,5-dichloro-1-cyclohexene with SF5Cl followed by dehydrochlorination [see Organic Letters, Vol. 6 (2004), pp. 2417-2419 and PCT WO 2004/011422 A1]; and (7) reaction of SF5Cl with acetylene, followed by bromination, dehydrobromination, and reduction with zinc, giving pentafluorosulfanylacetylene, which was then reacted with butadiene, followed by an aromatization reaction at very high temperature [see J. Org. Chem., Vol. 29 (1964), pp. 3567-3570].
Each of the above synthetic methods has one or more drawbacks making it either impractical (time and/or yield), overly expensive, and/or overly dangerous to practice. For example, synthetic methods (1) and (4) provide low yields and require expensive reaction agents, e.g., AgF2 and XeF2. Methods (2) and (3) require the use of F2, CF3OF, or CF2(OF)2, each of which is a toxic, explosive, and/or corrosive gas, and products produced using these methods are at a relatively low yield. Note that handling of these gasses is expensive from the standpoint of production, storage and use. In addition, synthetic methods that require the use of F2, CF3OF, and/or CF2(OF)2 are limited to the production of deactivated arylsulfur pentafluorides, such as nitrophenylsulfur pentafluorides, due to their extreme reactivity, which leads to side-reactions such as fluorination of the aromatic rings when not deactivated. Methods (5) and (6) also require expensive reactants, e.g., SF5Cl or SF5Br, and have narrow application because the starting cyclohexene derivatives have limited availability. Finally, method (7) requires an expensive reactant, SF5Cl, and this method includes numerous steps to reach the arylsulfur pentafluorides (timely and low yield).
As discussed above, conventional synthetic methodologies for the production of arylsulfur pentafluorides have proven difficult and are a concern within the art.
Recently, useful methods have been developed for solving the problems discussed above (see WO 2008/118787 A1; WO2010/014665 A1; US 2010/0130790 A1; US 2011/0004022 A1; U.S. Pat. No. 7,592,491 B2; U.S. Pat. No. 7,820,864 B2; U.S. Pat. No. 7,851,646 B2). One of the key steps described in each of these methods is the reaction of an arylsulfur halotetrafluoride with a fluoride source such as various fluorides compounds including elements found in groups 1, 2, 13-17 and transition elements of the Periodical Table. In particular, hydrogen fluoride is a useful fluoride source for the industrial process because of its availability and low cost, and in addition, its liquid nature having a boiling point 19° C. The liquid nature of hydrogen fluoride is suitable for large scale industrial processes because of its transportability, fluidity, and recyclability compared to solids, such as the fluorides of transition elements. However, methods using hydrogen fluoride still have several drawbacks, including: (1) as hydrogen fluoride is severely toxic, the amount of hydrogen fluoride used for a reaction must be minimized for safety and for the sake of the environment; (2) there is evolution of a large amount of a gaseous, toxic, corrosive hydrogen halide such as HCl (bp of HCl, −85° C.) from the reaction of an arylsulfur halotetrafluoride and hydrogen fluoride; (3) in some cases, a low yield or less purity of the product is obtained, because byproducts such as chlorinated arylsulfur pentafluorides are formed by side-reactions. These drawbacks cause significant cost problems in the industrial production of arylsulfur pentafluorides.
The present invention is directed toward finding more suitable methods to produce arylsulfur pentafluorides in an industrial scale and overcoming one or more of the problems discussed above.